As is already known from the DE 25 44 129 A1, the use liquid jets as a means for cutting or grinding various materials has been long known. The first publication about this topic deals with cutting rock formations and coal deposits. In addition to cutting with a continuous jet, cutting with a pulsed jet has proven itself useful because of the possibility to reach higher cutting and separating pressures. The speed at which the water jet leaves the nozzles amounts to at least 30 m/s. The pressures of the liquid are mostly in the order of magnitude of 3.times.10.sup.8 Pa. Basically the cutting of metal bodies up to thickness of about 200 mm is also possible and has already been practiced. In order to enhance the cutting effect, it has been proposed to add to the liquid, mostly a water jet, a chemical additive or abrasive agent, e.g. garnet sand (see DE 44 22 769 A1). The disadvantage here is the relatively long cutting process. For this reason a cutting torch is used for cutting slabs.